I will be getting 2 young guinea pigs soon and I'm wondering if I should start feeding them veggies right away, or if I should slowly introduce them to new things? They will be from the pet store (please don't shun me, I've already looked in shelters and there aren't any close to me) and I'm not sure how old they'll be. I know they aren't that old though, they're VERY tiny. So should I just launch straight into feeding them all sorts of veg or should I slowly introduce it? I don't want them to be malnourished.